Experimental Mammary Gland Growth in Rabbits by Estrogen and Progesterone.

Abstract

Daily injection of 9 [mu]g of estradiol benzoate for 20 days induced extensive development of the mammary duct system of male rabbits with negligible lobule formation. With male rabbits pretreated with estrogen to develop the duct system, the daily injection of 15 ug of estradiol benzoate combined with 1 mg of progesterone (synergistic ratio 167) induced the extensive development of the lobule-alveolar system as indicated by the DNA content and by visual examination of whole mounts of the glands. These observations indicate that the optimum synergistic ratio of the ovarian hormone in lobule-alveolar development in the rabbit differs widely from the ratio of 1:1000 or more seen in the mouse, rat and dog.